1. 地质过程与矿产资源国家重点实验室和地下信息探测技术与仪器教育部重点实验室，北京 100083
2. 中国地质大学（北京）地球物理与信息技术学院，北京 100083
3. Center for Gravity, Electrical, and Magnetic Studies, Department of Geophysics, Colorado School of Mines
The 3D magnetic structure beneath the continental margin of the northeastern South China Sea
Li Shu-Ling1,2,3, Li Yao-Guo3, and Meng Xiao-Hong2
1.State Key Laboratory of Geological Processes and Mineral Resources, and Key Laboratory of Geo-detection, Ministry of Education, Beijing, 100083, China.
2.School of Geophysics and Information Technology, China University of Geosciences, Beijing, 100083, China.
3.Center for Gravity, Electrical, and Magnetic Studies, Department of Geophysics, Colorado School of Mines, CO 80401, USA.
Abstract：
Understanding the continental margin of the Northeastern South China Sea is critical to the study of deep structures, tectonic evolution, and dynamics of the region. One set of important data for this endeavor is the total-fi eld magnetic data. Given the challenges associated with the magnetic data at low latitudes and with remanent magnetism in this area, we combine the equivalent-source technique and magnetic amplitude inversion to recover 3D subsurface magnetic structures. The inversion results show that this area is characterized by a north-south block division and east-west zonation. Magnetic regions strike in EW, NE and NW direction and are consistent with major tectonic trends in the region. The highly magnetic zone recovered from inversion in the continental margin differs visibly from that of the magnetically quiet zones to the south. The magnetic anomaly zone strikes in NE direction, covering an area of about 500 km × 60 km, and extending downward to a depth of 25 km or more. In combination with other geophysical data, we suggest that this strongly magnetic zone was produced by deep underplating of magma associated with plate subduction in Mesozoic period. The magnetically quiet zone in the south is an EW trending unit underlain by broad and gentle magnetic layers of lower crust. Its magnetic structure bears a clear resemblance to oceanic crust, assumed to be related to the presence of ancient oceanic crust there.
LI Shu-Ling,LI Yao-Guo,MENG Xiao-Hong. The 3D magnetic structure beneath the continental margin of the northeastern South China Sea[J]. APPLIED GEOPHYSICS, 2012, 9(3): 237-246.
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2012, Vol. 9 
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